Method of treating sheets of paper to increase their flexibility.



PATENTED MAR. 5, 1907,

.. R. L. GRAIN.

METHOD OF .TREATING SHEETS OF PAPER TO INCREASE THEIR FLEXIBILITY.

."LPPLIGATION FILED 0GT.3, 1906.

FIG. I

FIG-.4.

v wrrnnssns vTmaZZ whom it Jaw/y concern: EBe; it knownthat I, ROLLA L. GRAIN, of :Qttawa, inthe county ofCarleton, Province of" Ontario, Canada, have invented certain UNITED STATES PATENT OFFICE.

flno LA L. GRAIN, or OTTAWA, ONTARIO, CANADA.

METHOD OFTREATING SHEETS OF PAPER TO INCREASE THEIR l LEXlBlLlTY.

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Specification. of L tters Patent.

Patented March 5, 1907.

Application filed October 3, 1906. Serial No. 337,316.

new and'useful Improvements in Methods of Treating Sheets .of Paper to Increase 'l heir Flexibility, of which the following is a specifis 1 cation.-

My invention relates to a method for rendering portions of sheets of paper more flexible; and the objects of my invention are to render the sheets of paper used in loose-leaf binders more flexible along the bending-line, whereby when open the book willlie flatly and evenly. binder considerable difiiculty has been experienced in-endeavoring to cause the leaves to lie fiat while thebook is open at any given page. The paper of which the leaves are formed has necessarily to be fairly stifi', which prevents" it bending readily to lie flat against the covers of the book.

Byiny invention I am enabled to retain the desirable Stiff qualities of the paper by increasing its flexibility only along that portion in which the bending takes place, leaving the remainder with its original stiffness.

The invention is carried out by pressing a V series of corrugations in the portion of the paperdesired to be rendered more flexible, then pressing a second series of corrugations over the first in such a manner that each corrugation of the first series will be reformed on the reverse side of the paper, and then pressing the corrugations out, leaving the paper flat and smooth, the details of the method being more fully set forth and described in the accompanying specifications and drawings. I

Figure 1 is a plan of a sheet after the first series of corrugationshave been pressed in it, the size of the corrugations being exaggerated to more clearly indicate their nature.

Fig. 2 is a sectional view through the same. Fig. 3 is a sectional view after the second series of corrugations have been pressed in the paper. 1 Fig. a is a sectional view of the paper with the corrugations finally pressed out. Fig. 5 is a sectional detail through the surface of two dies which may be used to produce'the first series of corrugations. Fig. 6 is a sec: tional view through the surface of two similar dies which may be used to produce the second series of corrugations. Fig. 7 is a sectional view through two dieswhich may be used to press out the corrugations.

In using the ordinary loose-leaf In the drawings like letters of reference indicate corresponding parts in each figure.

In carrying out the method the separated sheet is first placed between the two (lie-surfaces of the form shown in Big. 5, which when brought together are adapted to form a series of corrugations in the paper, as indicated in Fig. 1. While these die-surfaces may be ordinary flat dies, I find it preferable. to accelerate the speed of the operation by forming them on the surface of rollers through which the sheet of paper is passed. 'lhe sheet of paper is next subjected to the action of the other pair of die-surfaces, (indicated in Fig. 6,) which reverses the corrugations first formedthat is to say, where the corrugation or ridge in the first case protruded from one side oi the paper it will now be reversed to protrude from the other-the paper thus being stretched in both operations. These die-surfaces are also preferably formed on rollers which may, if desired, be suitably situated with regard to the first-mentioned rollers, so that the paper may pass continuously through the two rollers.

In place of using a separate set of dies the same result might be accomplished by turning the sheet of paper over and operating on it. again by the first set of dies. Where rollers are employed, the paper would simply have to be turned upside down and passed through the rollers again. 7

Where it is not necessary to have a smooth surface for the paper, the operation of my method may at this point be considered to be complete. since the portion of the paper at which the bending occurs has been stretched from one side to the other, rendering it much more flexible. -The corrugations remaining in the paper, however, would have the disadvantage of causin it to be more bulky when inserted in the 00k, and so I prefer to remove all traces of the corrugations by operating on the paper by apair of flat dies, as shown in Fig. 7, preferably in the form of rollers. By the operation of this method the paper is stretched an equal amount to both sides and finally returned to its original position, leaving it practically ungations and their reversal.

It will be readily seen that the iethod might be carried out in a number of dili'erent machines, and, in fact. I have devised a machine in which the operation may be carried out continuously, and for which I intend shortly to file a patent application.

It is obvious that the corrugations formed in the paper may be of any slmpedesircd, and while in the sheets illustrated they are shown continuous, yet they might be made in separate portions, the essential feature being that the portions of the paper are first stretched to one side and then to the other. Thus in place of corrugations a number of consecutively-placed independent de-v pressions might-be used of round or other outline.

W'hat Iclann asmy 111vent1on .1s

l. The herein-described method of forming .a flexible band across a sheet ofpaper which consists in operating on the paper wlth a set-- of dies to produce a series of corrugations, protruding from one side thereof, then operating on the paper with a second-set of dies which exactly reverse each individual corrugation-formed by the iirst. set, whereby the paper forming the corrugation on one side will. now be stretched to form the corrugation on the opposite side substantially as described. 7

2. The herein-described method of treating a sheetof paper to increase its flexibility which consists in forming a corrugation in the paper on one side, then reversingthe corrug'ation so that it protrudes from the opposite side and then removing the corrugations and smoothing the paper substantially as described.

3. The herein-described method of treating a sheet of paper to increase its flexibility which consists,in forming a series of parallel corrugations in the paper on one side thereof,

then reversing the series of corrugations so that each corrugation protrudes from the opposite side to which it previously did and then removing the corrugations and smoothing the paper substantially as described.

4. The herein-described method of treating a sheet of paper to increase its flexibility "site side and then smoothing the paper and causing the stamped portion to again lie flat with the remainder ot'the sheet substantially as described.

Signed at Ottawa, in the Province of ()n tario', this 29th day of September, 1906.

ROLLA L. CRAIIN.

itnesses;

RUSSEL S. SMART. MAY LYON. 

